1. Field of the Invention
The present invention relates to a liquid transfusing bottle and more particularly to improvement of or relating to a liquid transfusing bottle made of synthetic resin in which liquid to be transfused such as glucose solution solusion, physiological aqueous solution of salt, Ringer's solution or the like is contained.
2. Description of the Prior Art
A hitherto known liquid transfusing bottle of the above-mentioned type is generally constructed in the form of a glass bottle with a rubber plug fitted thereto. However, due to reduced strength at time when it falls down on the floor or ground and inconvenience of handling of the glass bottle having a heavy weight, the conventional glass bottle is widely replaced with a liquid transfusing bottle (hereinafter referred to simply as a bottle) made of synthetic resin in recent years. It is true that the problems concerning reduced strength at time when the bottle falls down on the floor or ground and reduced dead weight of the bottle have been resolved by employing synthetic resin, but there is still a necessity for using an air venting needle adapted to be pierced through the rubber plug, the bottom wall or the like. As is well known, the air venting needle is intended to prevent the flow of liquid to be transfused (hereinafter referred to simply as liquid) from being stopped under the influence of negative pressure in the bottle which is caused as the liquid is consumed therefrom. But a problem is that dust or like foreign material in the air is introduced into the interior of the bottle together with air as the latter flows through the air venting needle.
As a countermeasure against the problem of introduction of foreign material into the liquid there has been already proposed a so-called closed type bottle (bottle of the type using no air venting needle). In order to inhibit the interior of the proposed bottle of the above-mentioned type from having negative pressure as liquid is consumed therefrom, the bottle is so constructed that the outer wall is flexibly deformed to reduce its diameter in conformance with consumption of liquid and thereby the inside volume of the bottle decreases correspondingly. However, since the conventional bottle is so designed that the outer wall surface of the barrel portion is located flush with the outer surface of the bottom portion and the shoulder portion, elastic deformation is carried out in such a manner that as liquid is consumed, first the barrel portion starts its deformation at the central area thereof to reduce its diameter and both the bottom portion and the shoulder portion are then deform gradually without occurrence of reduction of volume in proportion to consumption of liquid. This leads to such a state that the interior of the bottom is still maintained under the influence of negative pressure, resulting in a comparatively large volume of liquid being left unused in the bottle.
To obviate the foregoing problem there were made proposals, one of them disclosed in U.S. Pat. No. 3,325,031. This proposal is concerned with a bottle made of synthetic resin of the type including a barrel portion having a substantially elliptical crosssectional configuration which is characterized in that at least one of the bottom portion and the shoulder portion has an outer surface which is projected outwardly of the outer surface of both the front and rear sides of the barrel portion, whereby an annular stepped portion adapted to be deformed inwardly is built so as to form a diameter reduction promoting area at the position located in the proximity of both the bottom portion and the shoulder portion.
As a result of the arrangement made in that way it is assured that a residual volume of liquid left unused in the interior of the bottle at the final time of consumption of liquid is reduced remarkably and thereby liquid is consumed effectively.
In spite of the proposal as mentioned above which has a characterizing feature that a residual volume of liquid can be reduced, it has been found that the conventional bottle has still problems of malfunctioning such as distortion of the bottle, breakage of the same or the like in the course of deforming of the bottle in the form of diameter reduction from the starting time of consumption of liquid to the end of the same, resulting in smooth consumption of liquid at a high speed failing to be achieved, and moroever it takes an appreciably long time to discharge liquid.